Although grbl machines aren’t my forte, you really need to give us more information. When it stops does it loose power..?
Usually the console in Lightburn will give you some kind of error message or think it’s completed the job. The console may not be visible, you may have to click on Window on the top tool bar to enable the console. It will be a tab in the cut/layer window.
I don’t see anything in your project file that I think could cause an issue.. all setting seem reasonable.
You are only giving it <15mm to get to speed, don’t know if grbl is smart enough to flag this as an error. You’d have to figure out what your acceleration values are to use any of the on-line calculators.
If your speed is set for 50mm/s with an acceleration value of 50mm/s^2, then you need about 25mm to get to speed. These are older machines, so you acceleration values will likely be different. If you use the console and type $$ it should echo all of these variables.
There is a relatively easy way to check, moving the image >25mm away from the edge, as long as it has time to speed up/change directions and slow down. It wouldn’t hurt to make it further away to ensure you’re not too close.